Australia have been dealt a fresh injury blow ahead of Saturday's one-off Test against Ireland in Brisbane with the news that veteran lock Nathan Sharpe wwill miss the game with a back complaint.

Sharpe, the Wallabies' best performing forward in the opening three Tests of the campaign, suffered a twinge in his lower back during training on Tuesday and was unable to recover sufficiently.

Experienced Brumbies lock Mark Chisolm will replace the 82-Test veteran in the starting side with the uncapped Mitchell Chapman in line to make his international debut after he was promoted to the bench.

Chapman, who started off his Super Rugby career in Brisbane with the Queensland Reds in 2005 before switching to the Brumbies three seasons later, featured in the second row for the Australian Barbarians in both of their recent tour matches against England.

Sharpe, who missed last season's spring tour of Europe with a shoulder injury, joins a star-studded Wallabies casualty list.

Wing Digby Ioane (shoulder) and half-back Will Genia (thumb) will also miss the Lansdowne Cup Test with injuries suffered in last week's loss to England.

Genia is expected to return for his side's opening Tri Nations Test against South Africa in Brisbane on July 24 alongside prop Benn Robinson (arm) and hooker Stephen Moore (jaw). But the news is not so good for Ioane who was the latest player to be ruled out of the upcoming Tri Nations campaign after undergoing shoulder surgery on Tuesday.

Hooker Tatafu Polota-Nau (ankle), prop Ben Alexander (knee), lock James Horwill (knee) and No.8 Wycliff Palu (knee) will also miss the upcoming matches against the Springboks and All Blacks.

However, there was a welcome boost for the Wallabies with the news that winger Digby Ioane does not require surgery on his injured shoulder as first thought. The Reds paceman was originally ruled out for four months after sustaining the injury in the 21-20 loss to England in Sydney. But he is now battling to be back in action in time for the Tri-Nations next month.